Distributor system and method for optical fibers

ABSTRACT

Certain embodiments of a device for coupling fibre optic cables include at least one module equipped with at least one retaining unit for retaining at least two cassettes. Each cassette, which is configured with at least one coupling element, is pivotally and removeably attached to the retaining unit. Each cassette is configured to receive and store an excess length of the first optical fiber from the receiving structure.

This application is a Continuation of U.S. Ser. No. 10/531,146, filed 29Mar. 2006, which is a National Stage of PCT/EP2003/012119, filed 31 Oct.2003, which claims benefit of Serial No. 102 55 561.3, filed 22 Nov.2002 in Germany and which applications are incorporated herein byreference. To the extent appropriate, a claim of priority is made toeach of the above disclosed applications.

BACKGROUND

It is known to couple optical fibers in cassettes. Cassettes for thecoupling of optical fibers are known for example from U.S. Pat. No.6,282,360 B1, the cassette being able to receive the optical fibers withan excess length for a splicing reserve. Cassettes of this type are tobe designed in such a way that at least two cassettes can be stacked oneon top of the other to form a module and the excess length of theoptical fiber can be received while maintaining a minimum bendingradius. For access to an optical fiber, it is in this case known to formthe cassette in such a way that it can be pivoted in relation to themodule.

In addition, EP 0 474 091 A1 discloses a pothead arrangement for opticalfibers, comprising two shells connected to each other, the first shellbeing formed with a splicing element. For access to the splicingelement, the shells are displaceable in a plane in relation to eachother, the first shell receiving an optical fiber splicing reserve, thesecond shell receiving an optical fiber operating reserve and theoptical fiber being arranged in such a way that it is capable of beingtrailed via a guide duct.

A distributing unit is generally formed by a number of modules. It isoften not possible to work on the optical fibers at an installationlocation of the module in the distributing unit. In particular, splicingof optical fibers on splicing elements of a cassette preferably takesplace at suitable splicing locations. It is therefore known to transporta module which is in operation and in which the corresponding cassetteis mounted to a suitable workplace. A buffered fiber fed to the moduleis for this purpose formed with an excess length, so that, on the basisof removal of the module from the distributing unit and transport to theworkplace, the buffered fiber can yield correspondingly. However,mechanical loading of the buffered fiber on account of the movement isunavoidable. It is disadvantageous in this case that even access toindividual circuits comprising only a few optical fibers requires theentire buffered fiber, and consequently also the other circuits, toundergo loading on account of the movement.

SUMMARY

The invention is therefore based on the technical problem of providing adevice for coupling optical fibers bundled together in buffered fibers,with access to a subsystem, comprising at least one optical fiber, beingpossible at a workplace which is away from an installation location ofthe device without this affecting the other optical fibers.

A buffered fiber which can be divided into at least two strands, onestrand comprising at least one optical fiber, is fixed on a module. Acable tie and/or snap-in lugs provided on the module are conceivable,for example, as fixing for the buffered fiber on the module. The moduleis formed with at least one receiving device, which can receive at leasttwo cassettes. The module allows the cassettes to be arranged in acompact fashion. A strand with excess length can be received by thecassette and the at least one optical fiber of the strand can beconnected to a coupling element of the cassette. For working at aworkplace, a cassette with a received strand can be separated from themodule at the receiving device in operation. In this case, the opticalfibers of the associated strand are moved, the excess length reaching atleast from the installation location to the workplace. The bufferedfiber and/or further strands on the other hand are not adverselyaffected by access to the cassette. An empty cassette can likewise beremovable from the module, which is of advantage for example forexchanging defective cassettes. A number of modules can be combined toform a distribution system, it being possible for a buffered fiber to bedivided between a number of modules and/or for a number of bufferedfibers to be received by one module. It is evident that the excesslength of the buffered fiber known in the prior art is divided among thestrands in the individual cassettes, it then being possible for thebuffered fiber itself to be fixed without an excess length.

In a preferred embodiment, the cassette is formed with at least oneguide element, the guide element defining at least one path forreceiving at least one strand and a minimum radius of curvature of thepath being greater than a minimum-permissible bending radius of thestrand. The guide element is preferably formed in such a way that thewinding direction of an optical fiber of the strand is reversible, sothat two optical fibers of the strand can be connected by their endscoaxially to the coupling element.

In a further embodiment, the optical fibers of a strand are assigned toa circuit or circuits dependent on one another. During operation, thecassette to which the strand for forming the circuit and/or thedependent circuits is fed can be removed for access to the circuits.Circuits independent of this are not, however, adversely affected bythis access.

In a preferred embodiment, the cassettes are formed as single-fibercassettes, to which a circuit can be assigned. To form the circuit, twooptical fibers can be connected to each other by the coupling element.In this case, both optical fibers can be fed to the cassette as a commonstrand, it being possible for the strand to be formed by one or twobuffered fibers. In addition, it is also conceivable for the opticalfibers to be fed to the cassette through different openings, with forexample only one optical fiber being taken from the buffered fiber andfed to the cassette as a strand.

In a further embodiment, the coupling element of the cassette can beconnected to an optical fiber element which is formed with a plug-incontact, at least at an end remote from the coupling element. By meansof the coupling element, the optical fiber element can be connected tothe strand, i.e. to at least one optical fiber of the buffered fiber.The connection of the optical fiber element to the coupling element canbe established for example before the module is put into operation. Theplug-in contact allows a detachable connection to be established quicklyand reliably between the strand and an external optical fiber and/or adevice which are formed with a plug-in element complementing the plug-incontact. The cassette therefore has great flexibility. In this case, theplug-in connection can subsequently be replaced by a fixed connection,and vice versa. On account of the fact that the buffered fiber itself isnot moved during this necessary conversion work, the conversionperformed on a cassette has no repercussions for the rest of the module.

For this purpose, the plug-in contact with the associated optical fiberis simply disconnected at the coupling element and removed. Similarly,the associated patch cable with its complementary plug-in element isremoved and a new optical fiber is subsequently connected by means ofthe coupling element to the optical fiber of the cassette, the other endof which is firmly connected to a device.

In a further embodiment, the coupling element is formed as a splicingelement. A splicing element allows optical fibers to be connected in areliable and simple way.

In a further embodiment, a receiving device of a cassette comprisesthrough the module a guide rail, which can be firmly connected to themodule. The cassettes are received by the guide rails in uniquelydefined positions.

In a further embodiment, the receiving device of the cassette comprisesa pivoting mechanism. Removal of the cassette is often not necessary forcarrying out work on circuits. The pivoting mechanism has the effectthat individual cassettes can be pivoted out of a module plane into aworking area, optical fibers taken up by the movement only beingsubjected to low mechanical loading. A pivoting movement can be limitedfor example by stops and/or by guide grooves.

For this purpose, the pivoting mechanism is preferably formed with atleast one spindle, by which the cassette can be received. For thispurpose, the cassette is formed with a groove, by which the cassette canbe connected transversely to the direction of the spindle to the latter.In addition, it is also conceivable to form the cassette with anaperture, so that the cassette can be fitted onto the spindle in theaxial direction.

In a further embodiment, the receiving device of the cassette is formedby the module with a knurled screw. The knurled screw has the effectthat the cassette can be fixed on the module in at least one position inthe module plane.

Instead of the knurled screw, it is also conceivable to provide snap-inlugs on the module and/or on the cassette.

In a further embodiment, the cassette is formed with a receivingelement, by which at least one optical fiber with a fiber protection canbe received. If optical fibers are sheathed with a fiber protection,they often can no longer be received in the intended paths of thecassette. A corresponding element, which can for example be fitted ontothe cassette, has the effect that the optical fibers can be protectedbetter during transport to a workplace.

The device is preferably an element of a telecommunications distributionsystem.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained in more detail below on the basis of apreferred exemplary embodiment. In the figures:

FIG. 1 shows a schematic representation of a module comprising a numberof cassettes which are formed as through-splicing cassettes,

FIG. 2 a shows a detail from a plan view of a receiving device and acassette according to FIG. 1,

FIG. 2 b shows a side view of the receiving device according to FIG. 2a,

FIG. 3 shows a schematic representation of a module comprising tencassettes, which are respectively formed with a plug-in contact,

FIG. 4 a shows a detail from a plan view of a receiving device and acassette according to FIG. 3 and

FIG. 4 b shows a detail from a side view of the elements according toFIG. 4 a.

DETAILED DESCRIPTION

FIG. 1 schematically shows a module 1 comprising cassettes 2 andreceiving devices 3. The cassettes 2 are formed as single-fiberthrough-splicing cassettes, i.e. each cassette 2 can be assigned acircuit comprising two optical fibers. The optical fibers are formed forexample as fiber-optic cables.

Optical fibers (not represented) which can be assigned to the module 1are bundled together in a buffered fiber (likewise not represented). Thebuffered fiber can be fed to the module 1 via an opening 12. At theopening 12, the buffered fiber can be fixed, for example by cable ties.The buffered fiber is subdivided inside the module 1 into strands(likewise not represented), each strand preferably comprising twooptical fibers. In addition, it is also conceivable to feed a number ofbuffered fibers to the module 1 through the opening 12. The bufferedfibers can in this case again be subdivided into strands, strands beingable to comprise optical fibers of the same buffered fiber or differentbuffered fibers. The strands can be fed to the cassettes 2 throughchannels 13.

In the cassette 2, the optical fibers are laid along paths, which aredefined by guide elements 22, 23, 24. In this case, the paths of the twooptical fibers differ in such a way that a winding direction of anoptical fiber is changed, so that the ends of the optical fibers can beconnected coaxially in a coupling element 26.

For a connection of the optical fibers, the coupling element 26 isformed for example as a splicing unit. A connection of optical fibers bymeans of a splicing unit is preferably established at a splicingworkplace. For this purpose, the associated cassette 2 can be removedfrom the module 1 and transported individually to a splicing workplace.For this purpose, the optical fibers are, for example, trailed along andmust be of a length which is adequate for this. The reception of theoptical fibers in the paths of the cassette 2 formed by the guideelements 22, 23, 24 is therefore formed in such a way that the opticalfibers can be received with excess length. In this case, the excesslength is chosen to correspond to the distance from the workplace plusthe splicing reserve. Since the cassettes 2 can be removed individuallyfrom the module 1, access to a circuit for example is possible withoutinfluencing other circuits which are in operation.

The receiving devices 3 are formed with guide rails 31, it beingpossible for the guide rails 31 to be connected to profiled bars 14 ofthe module 1 by means of clips 32. The guide rail 31 is formed withspindles 34, by which the cassettes 2 can be received. For this purpose,the cassettes 2 are formed with an aperture 27. The position of thecassette 2 on the guide rail 31 and consequently in the module 1 can befixed in a module plane by a snap-in lug 28. For access to a circuit,the corresponding cassette 2 can be pivoted about an angle φ from themodule plane into a working area. A movement of the cassette 2transversely in relation to the spindle 34 allows the cassette 2 also tobe removed from the module 1 and transported to a suitable workplace.

FIG. 2 a shows a plan view of a connection of the cassette 2 to thereceiving device 3. The reference numerals correspond here to FIG. 1. Inthe representation, the cassette 2 has been pivoted out of the moduleplane about the spindle 34 into the working area. The position of thecassette 2 can be fixed both in the working area represented and in themodule plane by the snap-in lug 28, which engages in snap-in grooves 35of the receiving device.

FIG. 2 b shows a detail of a side view of the receiving device 3. Thecassette 2 (not represented) engages with the groove 27 in an annulargroove 38 on the spindle 34. A translatory movement of the cassette 2along the spindle is restricted as a result.

FIG. 3 schematically shows a module 1′ for receiving cassettes 2′. Thesame reference numerals have been used for elements which correspond tothe elements from FIG. 1. One or more buffered fibers is or are fed tothe module 1′ through the opening 12 and subdivided into twelveindividual strands. Each strand in this case comprises only one opticalfiber. A strand can be fed to a cassette 2′ along a channel 13. In a wayanalogous to the cassettes 2 represented in FIG. 1, the cassettes 2′ areformed with guide elements for receiving the strand, which however arecovered by a receiving element 21. The strand can be connected to acoupling element, which is likewise covered by the receiving element 21.

Apart from the strand which can be fed to the cassette 2′ through thechannel 13, at least a second optical fiber 5 can be received by thecassette 2′. The optical fiber 5 can be connected by one end to thecoupling element. The other end of the optical fiber 5 is formed as aplug-in contact 52. A buffered fiber 51 of the optical fiber 5 is ledalong a path defined by guide elements in the cassette 2′.

The plug-in contact 52 allows the optical fiber 5 to be connected tofurther optical fibers 6 which are formed with a plug-in element 62complementing the plug-in contact 52. The connection to an optical fiber6 is therefore extremely flexible and can be adapted quickly to changingrequirements. The length of the buffered fiber 52 is to be chosen tocorrespond to the application. In the embodiment represented, contactswith further optical fibers 6 are established directly at the cassette2′. In addition, it is also conceivable to use the plug-in contact 52 toestablish a contact with a device which is away from the module 1′. Thelength of the buffered fiber 51 is to be adapted accordingly. For greatflexibility, the buffered fiber 51 is preferably formed with excesslength, which can be received in the cassette 2′ in the paths providedfor it.

The optical fibers are protected by the cassette 2′ and the module 1′against mechanical loading. If, however, the cassettes 2′ are removedfrom the module 1′ and transported to a workplace—for example a splicinglocation, the optical fibers must be partly removed from the cassette2′. To be able to protect the optical fiber better against mechanicalloads in this case, the optical fiber can be sheathed with a fiberprotection (not represented). However, optical fibers with fiberprotection cannot be received by the paths which are defined by theguide elements 22, 23 and 24 visible in FIG. 1. Instead, the cassette 2′is formed with the receiving element 21. Optical fibers with fiberprotection can be received by the receiving element 21.

A receiving device 3′ of the cassette 2′ through the module 1′ comprisesa guide rail 31′, which is connected by the clips 32 to the profiledbars 14 of the module 1′. In a way analogous to the cassettes 2represented in FIG. 1, the cassettes 2′ have grooves 27, by which theycan be fitted onto spindles 34 of the guide rails 31′. Knurled screws 36allow the position of the cassettes 2′ in the module plane to be fixedbetter.

FIG. 4 a shows a plan view of the connection of the cassette 2′ to thereceiving device 3′. The reference numerals correspond in this case toFIG. 3. In the representation, the cassette 2′ has been pivoted out ofthe module plane about the spindle 34 into the working area and removedfrom the module 1′. The position of the cassette 2′ both in the workingarea and in the module plane can be fixed by the snap-in lug 28, whichengages in snap-in grooves 35 of the receiving device. The connection isalso reinforced by the knurled screw 36. On the underside, the knurledscrew 36 is formed with a snap-in profile 37 (which cannot be seen),which complements a snap-in profile 29 on the cassette 2′.

FIG. 4 b shows a side view of the components according to FIG. 4 a. Forthe cassette 2′ to be received by the receiving device 3′, the cassette2′ is moved transversely in relation to the spindle 34, so that thegroove 27 engages in the annular groove 28 on the spindle 34. Atranslatory movement of the cassette 2 along the spindle is restrictedas a result. The knurled screw 36 is moved in the axial direction by ascrewing movement about the spindle 34. As this happens, the snap-inprofile 37 engages in the complementary snap-in profile 29. As a result,the cassette 2′ can be positively connected to the receiving device 3′.

Apart from the modules 1, 1′ represented, modules which have boththrough-splicing cassettes and cassettes with plug-in contacts are alsoconceivable. Since the cassettes can be removed from the modules at anytime, corresponding adaptation is also possible after installation forthe first time.

The modules are, for example, elements of a telecommunicationsdistribution system. By the removal of individual cassettes, access toan individual customer circuit is possible even after installation forthe first time, during operation, without influencing other customercircuits which are in operation.

LIST OF DESIGNATIONS 1 module 1′ module 12 opening 13 channel 14profiled bar 2 cassette 2′ cassette 21 receiving element 22 guideelement 23 guide element 24 guide element 26 coupling element 27 groove28 snap-in lug 29 snap-in profile 3 receiving device 3′ receiving device31 guide rail 32 clip 34 spindle 35 snap-in groove 36 knurled screw 37snap-in profile 38 annular groove 5 optical fiber 51 buffered fiber 52plug-in contact 6 optical fiber 61 buffered fiber 62 plug-in element

1. A device comprising: a receiving structure defining at least onechannel configured to receive a first optical fiber, the receivingstructure including a spindle; a first cassette configured to pivotallycouple to the receiving structure, the first cassette defining a grooveconfigured to cooperates with the spindle to form a pivot point aboutwhich the first cassette pivots from a first position to a secondposition, the first cassette also being configured to be separated andremoved from the receiving structure by pivoting the first cassette tothe second position and sliding the first cassette in a directiontransverse to the spindle until the spindle passes through an open endof the groove; wherein the first cassette is configured to receive andstore an excess length of the first optical fiber from the receivingstructure.
 2. The device of claim 1, wherein the first cassette includesa first coupling element configured to optically couple the firstoptical fiber to a second optical fiber.
 3. The device of claim 2,wherein the first coupling element is formed as a splicing unit.
 4. Thedevice of claim 2, wherein the first coupling element is configured toreceive first and second plug-in contacts.
 5. The device of claim 2,further comprising a second cassette configured to pivotally couple tothe receiving structure, the second cassette having a second couplingelement configured to receive and store a wound, excess length of athird optical fiber.
 6. The device of claim 5, wherein the secondcassette is removeably coupled to the receiving structure.
 7. The deviceof claim 5, wherein the second optical fiber forms a buffered fibercable with the first optical fiber.
 8. The device of claim 5, whereinthe first and second optical fibers form separate buffered fiber cables.9. The device of claim 1, wherein the receiving structure includes ahousing defining a cavity, wherein the first cassette is positionedwithin the housing when the first cassette is pivoted to the firstposition; and wherein the first cassette is positioned at leastpartially outside the housing when the first cassette is pivoted to thesecond position.
 10. The device of claim 4, further comprising aplurality of cassettes configured to pivotally couple to the receivingstructure.
 11. The device of claim 1, wherein the first cassetteincludes at least a first guide element defining at least one path forreceiving at least the first optical fiber, the path defined by theguide element including a minimum radius of curvature greater than aminimum-permissible bend radius of the first optical fiber.
 12. A devicecomprising: a receiving structure defining a channel and including aspindle; a first cassette pivotally mounted to the spindle of thereceiving structure, the first cassette including a splicing unit and atleast one guide element, the first cassette defining a groove having anopen end and a closed end, the groove being configured to receive thespindle of the receiving structure through the open end to mount thefirst cassette to the receiving structure, the closed end of the groovecooperating with the spindle to form a pivot point about which the firstcassette pivots, the first cassette being configured to pivot about thepivot point from a first position to a second position, the firstcassette also being configured to be separated and removed from thereceiving structure by pivoting the first cassette to the secondposition and sliding the first cassette so that the spindle passesthrough the open end of the groove in a direction transverse to thespindle; a first optical fiber extending through the channel in thereceiving structure to the first cassette, the first optical fiber beingrouted to the splicing unit by the guide element; and a second opticalfiber extending through the channel in the receiving structure to thefirst cassette, the second optical fiber being routed to the splicingunit by the guide element, wherein the second optical fiber is splicedto the first optical fiber and secured to the splicing unit of the firstcassette.
 13. The device of claim 12, wherein the receiving structureincludes a housing defining a cavity, wherein the first cassette ispositioned within the housing when the first cassette is pivoted to thefirst position; and wherein the first cassette is positioned at leastpartially outside the housing when the first cassette is pivoted to thesecond position.
 14. The device of claim 12, further comprising a secondcassette configured to pivotally couple to the receiving structure, thesecond cassette including a second splicing unit and at least a secondguide element, the second cassette being configured to receive and storea wound, excess length of a third optical fiber.
 15. The device of claim14, wherein the second cassette is removeably coupled to the receivingstructure.
 16. The device of claim 14, wherein the second optical fiberforms a buffered fiber cable with the first optical fiber.
 17. Thedevice of claim 14, wherein the first and second optical fibers formseparate buffered fiber cables.
 18. The device of claim 14, furthercomprising a plurality of cassettes configured to pivotally couple tothe receiving structure.
 19. A method comprising: pivoting a cassettefor storing excess optical fiber about a spindle of the receivingstructure from a first position to a second position; removing thecassette from the receiving structure by moving the cassette in adirection transverse to the spindle when the cassette is arranged in thesecond position; unwinding a length of at least a first optical fiberstored on the cassette; and transporting the cassette to a workplace.20. The method of claim 19, further comprising: coupling a secondoptical fiber to the first optical fiber when the cassette is at theworkplace; storing the first optical fiber and the second optical fiberon the cassette; returning the cassette to the receiving structure bymoving the cassette transverse to the spindle to arrange the cassette isthe second position; and pivoting the cassette back to the firstposition.